Men made $221,297 a year, while women made just $165,278. In fact, women’s earnings are just now reaching the level of what men made 20 years ago: $168,795. Women account for one-third of all doctors and half of medical school students.

The data the researchers used in calculating the gap can’t factor in a doctor’s speciality or practice type, which could account for some of the disparity. But they cautioned that it may not just be different choices women make. “Specialty and practice choices may be due to not only preferences of female physicians but also unequal opportunities,” the researchers told Bloomberg News.

But female doctors aren’t the only ones getting stiffed when it comes to making money.